The behavior of heat conduction calorimeters lies between that of true adiabatic of bomb calorimeters and isothermal calorimeters. The use of an R-C model of the calorimeter and the application of Laplace transforms has enabled us to predict the response to a variety of inputs. With this model, we have identified the air gap between the cell and cell holder as a major source of error in thermokinetic measurements. We also used the model to design a new sensor/cell system which (a) eliminates the air gap, (b) increases sensitivity with no significant increase in risetime, and (c) accepts all three currently used cell sizes, 0.3, 0.5 and 1 ml.